1. Field of the Invention
The invention is generally in the field of pozzolans used with hydraulic cement to manufacture concrete.
2. Relevant Technology
In modern concrete, pozzolans such as fly ash and volcanic ash are often used to replace a portion of Portland cement. Replacing a portion of Portland cement with pozzolan yields improved concrete with higher durability, lower chloride permeability, reduced creep, increased resistance to chemical attack, lower cost, and reduced environmental impact. Pozzolans react with excess calcium hydroxide released during hydration of Portland cement and therefore help prevent carbonation. However, there is a limit to how much Portland cement can be replaced with pozzolan because pozzolans generally retard strength development.